A single primary tubercle to each compound plate. Very small secondaries and granules forming zig-zag line down perradius.

Interambulacral plates wider than tall; with a single primary tubercle, positioned centrally, with sunken areole. At ambitus very much smaller secondary tubercles, usually two to a plate, flanking. A well developed naked interradial zone present aborally.

Tubercles imperforate and crenulate. On adoral surface areoles typically show a radial ornament.

Distinguished from Phymosomaby the very much greater number of elements forming aboral ambulacral plates (10-12 as opposed to 5-6), and by the sunken peristome and lack of phyllodes. Distinguished from Acanthechinusby having primary tubercles with decidedly incised areoles, often with radial ornamentation on those of the oral surface. It also has a proportionally larger apical disc.

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